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People who take antioxidant vitamins such as A, C and E -- long touted as protecting against cancer, heart disease and other health problems - don't live any longer, new research shows.

Worse yet, there is actually evidence that they die younger than people who don't take vitamins.

"Our findings contradict the findings of observational studies claiming that antioxidants improve health," said Goran Bjelakovic, a researcher at the Centre for Clinical Intervention Research at Copenhagen University Hospital in Denmark.

The research, published in today's Journal of the American Medical Association, should be of interest to the millions of consumers who regularly take vitamin supplements.

But Eva Lonn, a professor of medicine at the Michael G. DeGroote School of Medicine at McMaster University in Hamilton, said they should not panic.

"The message is not that you will die if you take vitamins. The message is that large doses of antioxidants in supplements don't help," she said.

Dr. Lonn also cautioned that these findings apply only to supplements containing high doses of antioxidants such as vitamins A, C, E and beta carotene.

The findings do not apply to multivitamins, she said. There are also clear benefits to supplements such as vitamin D and folic acid for pregnant women.

Others, however, said the findings should be dismissed outright because the methodology is so flawed.

"People should absolutely not be changing their behaviour based on this study," said Aileen Burford Mason, an immunologist and founding partner of the Holistic Health Research Foundation of Canada.

The new study is a meta-analysis, a compilation and reanalysis of published studies. In this case, researchers analyzed 68 studies involving 232,606 people. They found no significant effect on mortality linked to consumption of antioxidant supplements.

But when they focused only on the highest-quality studies --where participants were randomly given real vitamins or placebos -- the research team actually found a higher risk of death among people taking vitamins: 16 per cent higher for those taking vitamin A; 7 per cent for beta carotene and; 4 per cent higher for vitamin E. While vitamin C has no negative impact, it did not increase longevity, either. Of all the antioxidants examined, only selenium was associated with a reduction in mortality.

The actual cause of death in most studies was unknown and studies where there were no deaths were excluded. Critics of this kind of research have long complained that it focuses on people in ill health who are taking vitamin supplements, which makes the findings misleading for the general public.

Dr. Burford Mason said the increases in mortality "are so very slight that no one can draw conclusions." But of greater concern, she said, is that the studies in the meta-analysis featured a broad range of doses, duration and vitamins.

For example, the studies ranged in duration from 28 days to 12 years, the doses of vitamins ranged from 10 to 10,000 international units (IU) daily and no attention was paid to supplement quality.

"They're not comparing apples and oranges, they're comparing apples, eggs and elephants," Dr. Burford Mason said.

Antioxidants such as beta carotene and vitamins A, C and E are believed to protect the body from harmful byproducts called free radicals, atoms or groups of atoms that form in such a way as to cause cell damage. The free radicals damage DNA and are thought to play a role in everything from aging to cancer.

In the new paper, the research team did not pinpoint the biochemical mechanism that may increase the risk of death, but they speculated that perhaps "by eliminating free radicals from our organism, we interfere with some essential defensive mechanism."

According to a survey conducted for the Canadian Health Food Association, about 35 per cent of Canadians regularly take a daily multivitamin and 23 per cent take single vitamins daily.